Tokyo: Thousands of Japanese and US troops launched an intensive air and sea operation on Friday to recover bodies of those killed in the huge earthquake and tsunami that ravaged northeast Japan three weeks ago.
The grim search came as the government revealed that radiation from a nuclear power plant crippled by the twin disaster had been found in groundwater, with contamination already reported in the air, ocean and food.
Struggling to cope with its worst crisis since World War II, the nation was to pause at 2:46 pm (0546 GMT) to mark the moment when the seafloor quake struck on March 11, leaving almost 28,000 people dead or missing.
In the search for bodies, Japanese and US armed forces deployed 120 aircraft and 65 ships for a three-day search along the northeast coast, where houses, ships, cars and trains still lay scattered across the muddy wastelands.
A total of 24,000 military personnel were to join the massive sweep, media said. "The focus will be along the coastline, river mouths and land areas still submerged in sea water," a Japanese ground forces official said.
Prime Minister Naoto Kan was to address the nation and then on Saturday fly to the devastated port of Rikuzentakata, and "J-village", the base for hundreds of emergency crew who have battled at great risk to prevent a nuclear meltdown.
At the Fukushima atomic plant, which has been leaking radiation, workers readied to spray resin on the rubble of blast-hit reactor buildings as part of their tense stop-and-go effort aimed at shutting the plant down.
The environmental impact was worsening, with high levels of iodine-131 found in groundwater 15 meters (50 feet) below the plant`s reactor number one, and at more than 4,000 times the maximum safe level nearby in the Pacific Ocean.
The radiation -- which has already halted national shipments and exports of vegetables, dairy produce and other foods from four prefectures -- widened to beef, the Health Ministry said.
A sample of beef from Tenei in Fukushima prefecture, about 70 kilometres (40 miles) from the crippled nuclear plant, had shown 510 becquerels of radioactive caesium -- exceeding the 500-becquerel limit, the ministry said.
The government has assured the public that no water or food contamination had yet reached levels that would have an immediate impact on public health.
Top government spokesman Yukio Edano said: "I have been informed that a certain amount of radioactive substances has leaked into the groundwater. We will keep monitoring the impact on sea water and the surrounding environment."
Japan has resisted a nudge from the UN nuclear watchdog this week to widen the 20 kilometre evacuation zone around the nuclear plant and clear people out of the village of Iitate, 40 kilometres northwest of the facility.
Of the village`s 6,000 residents, 3,800 were still there on Thursday, said local official Takashi Kobayashi by telephone.
In parts of the village, people "are walking outside as usual, although everyone is wearing a mask", he said.
"We are aware that a high level of radiation has been detected. But residents feel it`s best to stay home. They can`t stay at relatives` places for a long time and they need to take care of their cattle and other livestock."
On the tsunami-hit coastline within the 20 km exclusion zone, up to 1,000 bodies were still lying amid the tsunami`s muddy debris, out of reach of rescue workers who cannot enter because of the high radiation, Kyodo News reported.
The bodies had been "exposed to high levels of radiation after death", one official was quoted as saying, and there was concern that they were now too contaminated to be safely recovered, or even to be cremated.
In Tokyo, meanwhile, cherry trees started to blossom, usually a treasured spring event that symbolises the fragility of life and which is normally celebrated with much food and drink in raucous picnics.
But any parties promised to be muted this weekend in the capital, where dimmed neon lights amid a national power shortage and half-empty shop shelves have added to the gloomy mood ever since the March 11 catastrophe.
Tokyo`s Ueno park, which usually attracts some of the largest crowds to revel below the "sakura" trees` pink canopy, has cancelled the parties for the first time since World War II, organiser Masahiro Kayano said.